Figure-8 Flanges: Smart Isolation for Critical Piping Systems
Release Time:
Jun 27,2025
Dual-Function Spectacle Blinds for Visual Flow Control and Safe Maintenance in High-Pressure Applications
FIGURE-8 FLANGE (Spectacle Blind Flange)
Structural Features:
A specialty flange accessory shaped like the number “8” (also known as Spectacle Blind) consisting of:
One solid end (Blind Plate) to block flow
One open end (Spacer/Ring) to allow flow
They are connected by a web or bridge, allowing easy switching between open and closed positions by rotating the flange set.
Installed between two flanges with standard bolting.
Installation & Usage:
Positioned between two pipe flanges using standard bolts
To stop flow, the solid plate is placed between flanges
To resume flow, rotate the figure-8 and align the ring side in position
A visual indicator of whether the line is “open” or “closed”
Designed for easy isolation of systems during maintenance
Applications:
Ideal for:
Permanent piping systems needing periodic flow isolation
Maintenance, inspection, or safety shutdowns
Situations where a clear status indicator is needed
Commonly used in:
Oil & Gas
Chemical Plants
Refineries
Power Generation Facilities
Offshore Installations
Common Size Standards:
Follows flange standards such as ASME B16.48
Dimensions compatible with ASME B16.5 / B16.47 flanges
Pressure Ratings:
Available in:
Class 150, 300, 600, 900, 1500, and 2500
Face Types:
Matches the facing of adjoining flanges: RF, RTJ, or FF
Materials:
Carbon Steel, Stainless Steel, Alloy Steel
Often matches the pipe or flange material for consistency
Can be coated or treated for corrosion resistance
Recommendation:
Figure-8 flanges are essential for safe and visual line isolation, especially in critical process systems.
They combine flow control and safety in one component, making them highly valuable for maintenance and operational visibility.
Recommended wherever manual and visual shut-off is required without removing flange connections.
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Cangzhou City, Hebei Province, China
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